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Játtað í: 2008 Granskingarøki: Náttúra og -tilfeingi Verkætlanarslag: Post.doc. Verkætlanarheiti: Iron Biogeochemistry in the high latitude North Atlantic Ocean Játtanarnummar: 0408 Verkætlanarleiðari: Maria Nielsdóttir Stovnur/virki: University of Southampton Verkætlanarskeið: Upprunaliga: 1.5.2009-31.4.2011 Endaliga: 1.5.2009-31.12.2012 Stuðul úr Granskingargrunninum: 1.000.000 kr.+125.171 kr. eykajáttan Verkætlanarlýsing: Original: The concentration of carbon dioxide has increased significantly since the start of the industrial revolution as a result of burning fossil fuel and deforestation. CO2 influences the climate on earth and its concentration is now so high that the earth’s atmosphere is warming and the weather is becoming more extreme. Phytoplankton take up CO2 from the atmosphere and that way help to reduce the atmospheric concentration. Phytoplankton cells also need nutrients like nitrogen, phosphorus and silicate to grow. Recently it has been discovered that the phytoplankton in for 40% of the world's oceans are lacking iron. For example, in the Southern Ocean the growth of the phytoplankton cells is limited by very low iron concentrations. Therefore, the phytoplanktons in this ocean do not remove as much carbon dioxide from the atmosphere as they could do under ideal conditions. Many people think that the high latitude North Atlantic Ocean receives enough iron through dust from the Sahara. However, recent experiments have shown that even in the North Atlantic phytoplankton cells lack iron. In this project, we want to study whether iron is limiting phytoplankton in the hight latitude North Atlantic at higher latitudes higher than 60oN. In order to achieve this, we will take part in research cruises and take samples of water and determine the physiological status of the phytoplankton communities. We will analyse iron and nutrients in the samples and calculate the supply ratios of iron to N, P, C to the surface oceans, and their ratios in sedimenting material. We will use models to aid us with the calculations for the oceanic transfer of these as elements. If the phytoplankton are iron limited in the high latitude north Atlantic then it will be because the amount of iron they get in relation to the nutrients is too low. We will also directly investigated whether iron is limiting the growth of phytoplankton in water samples from the high latitude North Atlantic. To find this out we will grow phytoplankton cells taken from the surface ocean in transparent bottles on the deck of the ship. We will add iron to some bottles, whereas other bottles will not receive any iron. In addition we will add radiolabelled 55Fe to the +Fe incubation bottles to access how the phytoplankton on a cellular level take up iron. The growth and physiological state of the phytoplankton will be determined using a number of measurements, such as chlorophyll concentrations. These measurements will show whether the bottles with added iron show a higher number of phytoplankton cells and higher growth, compared with the bottle to which no iron was added. The results of the proposed project will provide us with a better understanding of the role that nutrients like iron play in the growth of phytoplankton cells in the ocean. The gather data will help the computer modelers to design improved climate models that will allow us to better predict the extent of climate change over the next 100s of years. Final: The project ‘Iron Biogeochemistry in high latitude North Atlantic’ focused on the Iceland and Irminger Basin and how the growth and physiology of in situ phytoplankton community are controlled by the micronutrient iron (Fe). A novel carrierfree 55Fe was applied in the area for the first time spring and summer and the results are significantly different than previous studies in other iron limited areas. Uptake was dominated by the larger than 5 m during spring and by the < 5 m fraction during summer. Emiliania huxleyi is a calcifying coccolitophore that has been identified to create large visual blooms from space and which has been observed to be iron limited in the Iceland Basin. Experiments were conducted with E. huxleyi strains from seven different locations around the world, investigating the sensitivity to iron availability. E. huxleyi displayed large variability in its iron requirement depending on origin of isolation. Støða: Liðug Avrik: Scientific articles, books, thesis etc. Scientific article: A study of coastal and oceanic Emiliania huxleyi – growth rates and intracellular elemental quotas, submitted Scientific article: Carrierfree 55Fe in the high latitude North Atlantic- in progress Scientific article: Spatial and temporal development of phytoplankton iron stress in relation to bloom dynamics in the high latitude North Atlantic Ocean- published << Back |
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